Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
Thornton's September weather features a mild decline in high-temperatures, reducing from a moderately hot 83.5°F (28.6°C) in August to an agreeable 73.2°F (22.9°C). In September, Thornton records an average nighttime temperature of 52.9°F (11.6°C).Humidity
In Thornton, Washington, the average relative humidity in September is 46%.Rainfall
In Thornton, in September, during 6.4 rainfall days, 0.47" (12mm) of precipitation is typically accumulated. In Thornton, during the entire year, the rain falls for 120.2 days and collects up to 14.69" (373mm) of precipitation.Snowfall
Months with snowfall are January through May, September through December. September is the first month it typically snows. Throughout September, in the average 0.1 snowfall days, it receives 0.2" (5mm) of snow. Throughout the year, there are 39.6 snowfall days, and 22.68" (576mm) of snow is accumulated.Daylight
In Thornton, the average length of the day in September is 12h and 32min.On the first day of September, sunrise is at 6:09 am and sunset at 7:28 pm. On the last day of the month, sunrise is at 6:48 am and sunset at 6:30 pm PDT.
Sunshine
In Thornton, the average sunshine in September is 10.3h.UV index
The average daily maximum UV index in September is 4. A UV Index estimate of 3 to 5 represents a medium vulnerability from exposure to the Sun's UV radiation for the average person.Note: A maximum high daily UV index of 4 during September translates into the following directions:
Heed the precautions - Protecting the skin and eyes from damage is compulsory. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. Experience reduced UV exposure by about half when donning a wide-brim hat. Foresee this! The reflection from snow can nearly double the intensity of UV radiation from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature?
What is the average humidity in September in Thornton?
How much does it rain in September?
When does it start to snow?
What is the average length of the day in September?
When are sunrise and sunset in September?
How many hours of sunshine does Thornton have in September?
How high is the UV index in September?
Average temperature in September
Thornton, WA
- Average high temperature in September: 73.2°F
The warmest month (with the highest average high temperature) is August (83.5°F).
The month with the lowest average high temperature is December (34.7°F).
- Average low temperature in September: 52.9°F
The month with the highest average low temperature is August (60.4°F).
The coldest month (with the lowest average low temperature) is December (24.6°F).
Average pressure in September
Thornton, WA
- Average pressure in September: 29.96"Hg
The month with the highest atmospheric pressure is January (30.19"Hg).
The month with the lowest atmospheric pressure is August (29.91"Hg).
Average wind speed in September
Thornton, WA
- Average wind speed in September: 6mph
The windiest month (with the highest average wind speed) is March (8mph).
The calmest month (with the lowest average wind speed) is August (5.9mph).
Average humidity in September
Thornton, WA
- Average humidity in September: 46%
The month with the highest relative humidity is January (85%).
The month with the lowest relative humidity is August (37%).
Average rainfall in September
Thornton, WA
- Average rainfall in September: 0.47"
The wettest month (with the highest rainfall) is December (1.93").
The driest month (with the least rainfall) is July (0.28").
Average rainfall days in September
Thornton, WA
- Average rainfall days in September: 6.4 days
The month with the highest number of rainy days is April (14.6 days).
The month with the least rainy days is July (4.5 days).
Average snowfall in September
Thornton, WA
- Average snowfall in September: 0.2"
The month with the highest snowfall is February (6.69").
The months with the least snowfall are June, July and August (0").
Average snowfall days in September
Thornton, WA
- Average snowfall days in September: 0.1 days
The months with the highest number of snowfall days are February and December (9.6 days).
The months with the least snowfall days are June, July and August (0 days).
Average daylight in September /
Average sunshine in September
Thornton, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 48min).
The month with the shortest days is December (Average daylight: 8h and 36min).
- Average sunshine in September: 10h and 2min
The months with the most sunshine are July and August (Average sunshine: 12h and 0min).
The months with the least sunshine are January and December (Average sunshine: 4h and 36min).
Average sunshine days in September
Thornton, WA
- Average sunshine days in September: 22.4 days
The month with the most sunshine days is July (24.6 days).
The month with the least sunshine days is February (12.2 days).
Average UV index in September
Thornton, WA
- Average UV index in September: 4
The month with the highest UV index is July (UV index 7).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Thornton, WA
- Average cloud cover in September: 19
The months with the most cloud cover are January and December (Cloud cover 53).
The month with the least cloud cover is July (Cloud cover 11).
Average visibility in September
Thornton, WA
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February and December (5mi).
Thornton, Washington, USA
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